American Idol: Caleb Johnson and Jena Irene Rock It Out

American Idol's Top 9 unleashed their inner rock star Wednesday, tackling songs that fit into the theme "I'm with the Band."

While most of the performers hit some high notes in their performances, the theme was a perfect fit for a few singers who have already drawn comparisons to lead singers from legendary bands.

Leading the pack was Caleb Johnson, 22, who rocked the stage, going toe-to-toe with the band as they jammed "Dazed and Confused" by Led Zeppelin.

It's not easy to pull off Robert Plant's vocals, but Johnson electrified the audience with a performance Jennifer Lopez called "sexy."

"You wanna be the front man of the rock band, you have to have that," said Lopez. "You have that."

"I don't know how you could have sung that tune any better," said Harry Connick Jr. "I wish the song could've been eight minutes long," while Keith Urban said, "Your whole performance came at me like an airbag in slow motion."

Not to be outdone, Jena Irene, 17, who followed Johnson to close the show, also rocked the house, but with a modern edge, singing "Bring Me to Life" by Evanescence.

"You got your own lane, baby, like Caleb," said Urban, while Connick congratulated her for successfully following Johnson's big vocal. "This is a voice that can be heard on radio. It was really, really strong."

Tuba-playing teen Malaya Watson brought some old-school soul to the "The Long and Winding Road," a performance Urban said "showed me your spirit."

"Your voice stands out above everybody else's," Lopez said. "Your vibrato has the sweetness of a young Michael Jackson's."

"I give you the award for most consistently improving," Connick noted, before telling her to "work on the craft, forget stardom … you can really become something great."

Jessica Meuse's voice has been compared to Stevie Nicks's, so the 23-year-old took on one of her biggest hits, "Rhiannon," which Connick said "may have been my favorite performance you have done … I'm proud of you."

"I could listen to you sing all day," said Lopez, who urged her to show more emotion.

And if the performances weren't enough entertainment, the judges continued their wacky ways, which started when Connick encouraged Ryan Seacrest to shed a shoe and sock, a la Alex Preston, which he promptly stole and hid, leaving the host barefoot.

And after a rather harsh critique of Dexter Roberts, Urban offered up a giant gummy bear to sweeten up Connick, who quickly tore off an ear (later replayed in excruciating slow motion).

Lopez dug in as well, pulling off an ear, which she chewed for a moment before spitting it into her cup and replying, "It's like plastic with sugar."

Whose voices will be sweet enough to make it until next week? Tune in to see the results Thursday (9 p.m. ET) on Fox.